Battery unit

ABSTRACT

A battery unit (1) with a stack (2) of flat cells (3), with metal cooling sheets (4) between the cells, which have at least one bended edge (5), with the edges (5) of adjacent metal cooling sheets (4) aligned in the same direction and with the bending partially overlapping in order to form die gaps (6) which are also aligned in the same direction.

The present invention relates to a battery unit that contains a stack of flat cells, between which metal sheets are placed. Each metal sheet has at least one angled edge.

A similar battery unit is, for example, described in DE 10 2008 016 936 A2. There, the edges of the metal cooling sheets are bent at 90 degrees in order to cover the cells in a form-fitting way and to thereby provide a connection to a heat sink.

Battery units of this type can create levels of pressure inside the cells through overheating, short circuits, or other electrical incidents that cause the cells to burst and subsequently leak the gas that was created in the cells. This process can even lead to the formation of flames. If the flames spread to an adjacent cell, that cell may also overheat, resulting in a chain reaction that can pose a serious safety risk.

The goal of this invention is to create a battery unit inside of which the respective cells are better protected against gas leaks and flames.

This goal is achieved through a battery unit of the aforementioned type, which however, according to the invention, is characterized by adjacent metal cooling sheets having their edges angled in the same direction. Furthermore, these edges partially overlap in order to form die gaps, which are aligned in the same direction.

Thanks to these design features, any gas escaping from a cell is deflected to the side and diverted away from any adjacent—and any opposite—cells, so that these cells are effectively protected from the gases or flames emanating from a single faulty cell. This setup reduces the risk of a chain reaction and, as a result, enables the production of low-cost battery units with considerably enhanced levels of operating safety.

The angle of the bend is preferably greater than or equal to 45 degrees and smaller than 90 degrees. Most preferably, the angle is between about 70 degrees and 85 degrees in order to form a die gap that points as far as possible sideways.

When the battery unit is situated next to at least two adjacent stacks of cells, then the edges inside the battery unit are aligned in the same direction, especially if viewed in three dimensions, in order to protect the respectively opposite stack. In a particular variation of the invention, when the battery unit has at least two adjacent stacks of cells, edges that are opposite to each other in the battery unit are angled in the same direction or in a mirror-symmetric way in order to protect the respectively opposite stack.

Furthermore, the edge design of the present invention creates the possibility to curl the metal cooling sheets in an area close to the edges, so that the cells are protected against slipping towards the edges, which constitutes an additional preferable feature of the invention.

The invention is described in more detail in the enclosed figures and drawings, which present an implementation example. The drawings demonstrate

FIG. 1 a battery unit according to the invention with a cell stack from a perspective view;

FIG. 2 the edge area of the cell stack depicted in FIG. 1 from a top view; and

FIG. 3 the edges of a battery unit of two opposite stacks with multiple cell stacks from a top view.

FIG. 1 shows a battery unit 1 with a stack 2 of flat cells 3, between which the metal cooling sheets 4 are placed. The cells 3 can, for example, be Lithium-Ion cells, which are encapsulated in a plastic shrink-wrap and equipped with the appropriate electrical connections.

According to FIG. 2, the cooling metal sheets 4 each have an angled edge 5. The edges 5 of adjacent metal cooling sheets 4 are angled in the same direction and partially overlap. As a result, the edges 5 form die gaps 6 in the overlapping areas, which redirect any gases or flames emanating from the cells 3 to the side. I.e., the gases or flames are directed away from adjacent and opposite cells (see arrows 7 in FIG. 3).

The angle α formed between the metal sheets and their bent edges 5 is preferably greater than or equal to 45 degrees, but in any case less than 90 degrees, in order to create the die gaps 6. Preferably, the angle α is between 70 degrees and 85 degrees, and ideally around 80 degrees.

In areas 8 that are directly adjacent to the edges 5, the cooling plates 4 are curled in order to prevent the directly adjacent cells (s) from sliding all the way to the edges (5).

The invention is not limited to the illustrated implementation example, but includes all variations and modifications that fall within the scope of the claims listed below. 

1-4. (canceled)
 5. A battery unit comprising: a plurality of cells arranged in a stacked order; and a cooling sheet provided between adjacent cells, the cooling sheet having at least one edge which is bent at a predetermined angle and configured such that the at least one edge of adjacent cooling sheets are aligned spatially in the same direction and partially overlap in order to form a gaps in the direction of the alignment.
 6. The battery unit of claim 5, wherein the cooling sheet is composed of a metal material.
 7. The battery unit of claim 5, wherein the predetermined angle is greater than or equal to 45 degrees.
 8. The battery unit of claim 7, wherein the predetermined angle is less than 90 degrees.
 9. The battery unit of claim 5, wherein the predetermined angle is in a range of between 70 degrees and 85 degrees.
 10. A battery unit comprising: a first plurality of cells arranged in a stacked order; a second plurality of cells arranged in a stacked order and opposed to the first plurality of cells; a first cooling sheet provided between adjacent ones of the first plurality of cells, the first cooling sheet having at least one first edge which is bent at a first predetermined angle and configured such that the at least one first edge of adjacent first cooling sheets are aligned spatially in the same direction and partially overlap in order to form a first gap in the direction of the alignment; and a second cooling sheet provided between adjacent ones of the second plurality of cells, the second cooling sheet having at least one second edge which is bent at a second predetermined angle and configured such that the at least one second edge of adjacent second cooling sheets are aligned spatially in the same direction and partially overlap in order to form a second gap in the direction of the alignment, wherein the at least one first edge and the at least one second edge are bent in the same direction.
 11. The battery unit of claim 10, wherein the first cooling sheet is composed of a metal material.
 12. The battery unit of claim 10, wherein the first cooling sheet is composed of a metal material.
 13. The battery unit of claim 10, wherein the first cooling sheet and the second cooling sheet are composed of the same material.
 14. The battery unit of claim 13, wherein the first cooling sheet and the second cooling sheet are composed of a metal material.
 15. The battery unit of claim 5, wherein: the first predetermined angle is greater than or equal to 45 degrees; and the second predetermined angle is greater than or equal to 45 degrees.
 16. The battery unit of claim 15, wherein the first predetermined angle and the second predetermined angle is less than 90 degrees.
 17. The battery unit of claim 10, wherein: the first predetermined angle is in a range of between 70 degrees and 85 degrees; and the second predetermined angle is in a range of between 70 degrees and 85 degrees.
 18. The battery unit of claim 10, wherein the first predetermined angle is the same as the second predetermined angle.
 19. A battery unit comprising: a plurality of cells spaced from each other; and a cooling sheet provided in the space between adjacent cells, the cooling sheet having a first section at a base portion thereof, a second area at an distal portion thereof, and a third section between the first section and the second section, wherein: the second section is bent at a predetermined angle relative to the first section such that the second section of adjacent cooling sheets are aligned spatially in the same direction and partially overlap to define a flow path; and the third section is curled relative to the first section to thereby prevent a cell adjacent to one of cooling sheets from slipping towards the second section.
 20. The battery unit of claim 19, wherein the cooling sheet is composed of a metal material.
 21. The battery unit of claim 19, wherein the predetermined angle is greater than or equal to 45 degrees.
 22. The battery unit of claim 21, wherein the predetermined angle is less than 90 degrees.
 23. The battery unit of claim 19, wherein the predetermined angle is in a range of between 70 degrees and 85 degrees.
 24. The battery unit of claim 19, wherein the flow path directs at least gases away from the cells. 